1. Field of the Invention
This invention relates to medical endoscopes and, more particularly, to an improved electrode for use with a resectoscope and a method for making the same.
2. Prior Art
A typical resectoscope for transurethral resection consists of four main elements. The first element is a rigid telescope for observing the interior of the human bladder, or operative sites near the base of the urethra. The telescope comprises an objective lens and a series of relay lenses housed within an endoscope barrel or stem, the stem being connected to an eyepiece housing containing suitable lenses for proper magnification. The second element takes the form of a handle assembly commonly referred to as a working element. The working element can serve as the means for connecting electrosurgical current from an electrosurgical generator to the third element, an electrode assembly. The working element is also capable of slidably moving the electrode assembly axially, such axial movement being observable through the eyepiece of the telescope. The combination of the telescope, working element, and electrode assembly is locked into a fourth element, a resectoscope sheath. The sheath consists of a tube and a union body and lock assembly. In an operative procedure the sheath is placed into the urethra prior to introduction of the other elements.
The usual resectoscope electrode assembly takes the form of a U-shaped tungsten wire loop, the ends of the loop having integral spaced parallel wire arms which extend along, but are spaced from, the distal end of the rigid telescope. The wire arms usually merge at their proximal ends and are joined to an electrode lead extending back to the working element of the instrument. To brace the cutting loop so that it remains uniformly spaced from the telescope stem, a metal spacing sleeve is commonly provided between the telescope stem and either parallel electrode arms or the distal portion of the electrode lead immediately adjacent those arms. The metal spacing sleeve is slidable along the telescope stem as the electrode assembly is advanced and retracted and, because of the direct contact between the spacing sleeve and the telescope stem, it has been necessary in the past to insure adequate insulation between the electrode and the sleeve. Reference is made to U.S. Pat. Nos. 3,856,015, 3,901,242, 2,752,159, and 2,448,741 to illustrate prior cutting electrode assemblies.
U.S. Pat. No. 4,149,438 to Mrava et al discloses a plastic bearing tube for slidably engaging the rigid telescope stem of an instrument. Other electrodes in the prior art include members that have rigid seats that slidably sit on the rigid telescope stems and have a rigid stiffener over substantially the entire length of the electrode lead or merely a portion of the lead.
However, problems exist with electrodes of the prior art. Electrodes such as those disclosed in U.S. Pat. No. 4,149,538 must have the bearing tube slipped over the distal end of the telescope and do not have any type of stiffener for the distal region of the lead except for the bearing tube. Electrodes such as the ACMI model 4812U do not have any means for grasping onto the telescope. It merely has a seat for making sliding contact along the telescope.
It is therefore an objective of the present invention to provide an electrode with a distal end stabilizer that can either slip over the distal end of a telescope or resiliently snap onto the telescope.